PORTLAND, Maine — Justices on the Maine Supreme Judicial Court heard oral arguments Thursday in a case that pits 29 former Millinocket employees against the town over changes to their retirement benefits.

The employees are appealing a summary judgment handed down by Penobscot County Superior Court Justice Donald Marden last year. They argue that there are material facts in dispute, making the summary judgment an improper result of their breach of contract claim.

The plaintiffs, represented by John Hamer of Rudman Winchell in Bangor, have argued that the town breached their contracts when, in 2009, it changed its personnel policy, saying it would fund only 87 percent of their health insurance costs, according to case documents. Before that, the town had fully covered its employees’ and retirees’ health benefits.

“Any employment relationship is based on contractual obligations,” Hamer told the justices.

In 1991, the personnel policy was amended to say that the town had the right to change these benefits in the future, but those changes would affect only employees hired after Aug. 8, 1991.

Hamer argued that the policy change promised 100 percent coverage of health care for the rest of the life of any town employee hired before that date.

The town, represented by Jeffrey Piampiano of Portland’s Drummond, Woodsum & MacMahon, differs in its view of what that section of the personnel policy means.

Piampiano also argued that Millinocket’s policy is not a binding contract between the town and its nonunion employees, but rather an employee manual.

If questions remain about the language contained in the personnel policy, the case should go back to trial, Piampiano argued.